A CRT, representatively a TV Braun tube, is designed to have an electronic gun and a phosphor screen such that the electronic gun emits an electronic beam against the phosphor screen to excite the phosphor to be luminous. Recent developments of electronics make visual equipment more various require correspondingly various kinds of CRTs, such as monochromatic, multicolored, large size and very small.
The phosphor screen, in particular, the color phosphor screen is the most important factor for the efficiency of the CRT. The color phosphor screen is composed of dot-like or stripe-like disposition of red, green and blue phosphors so as to receive an electronic beam emitted by the electronic gun.
As the manufacturing methods for the phosphor screen, there have been conventionally known a photo-curing method employing a shadow mask and a printing method.
The former photo-curing method takes the steps of flowing a slurry having a light-curing resin and a phosphor dispersed therein in a front panel of the CRT, exposing the slurry through the shadow mask, fixing predetermined color phosphors at predetermined locations, and burning fixed resin components except the phosphor. Hence, the shadow mask is essential to this photo-curing method.
The latter printing method takes the steps of directly or indirectly printing color phosphor paste on the front panel of the CRT, fixing predetermined colors at predetermined locations, and burning binder-resin components contained in the paste.
Of the foregoing methods for manufacturing the phosphor screen, the shadow mask with fine patterns being engraved is essential to the former photo-curing method. Hence, as the CRT becomes smaller in size or more high-definition, the photo-curing method requires a finer shadow mask. Hence, when manufacturing a quite high-definition screen, it is technically difficult to manufacture the shadow mask therefor. The manufacturing cost of the shadow mask becomes high in the light of the material and the productivity. Moreover, the method for manufacturing a phosphor screen based on the photo-curing method using the shadow mask has some disadvantages that it is costly in the light of the equipment making it possible to execute the method, it needs a troublesome operation for recovering a phosphor, and it suffers from a loss.
The latter printing method is more industrially advantageous in the light of the equipment cost and loss of the phosphor in comparison with the photo-curing method. However, this printing method has some difficulty in directly forming a phosphor screen on the curve of the CRT or manufacturing a small-size high-resolution color phosphor screen requiring 0.1 mm or less fine stripe pattern in the light of a proper printing. Actually, hence, this printing method is not used for manufacturing a small-sized high-resolution phosphor screen as an industrial manufacturing method.